/***********************************************************************
 * BinTrotter : BitTorrent library/client for the Android operating system.
 *  
 * Copyright (C) 2009, Christopher David Stones (chris.stones@gmail.com)
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************/

package org.bintrotter.apeer.receivestates;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

import org.bintrotter.apeer.Peer;

public class MessageLength implements ReceiveState {

	private Peer 			m_peer;
	private int				msgLen;
	private byte[]			msgLenBytes;
	private SocketChannel 	sc;
	private ByteBuffer		bb;
	
	public MessageLength(Peer peer) {
		
		m_peer = peer;
		msgLenBytes = new byte[] {0,0,0,0};
		bb = null;
	}
	
	public int length() {
			
		return msgLen;
	}
	
	@Override
	public void reset() {

		msgLen = -1;
		sc = m_peer.channel();
		if(bb==null)
			bb = ByteBuffer.wrap(msgLenBytes);
		else
			bb.clear();
	}

	@Override
	public States update() {

		try
		{
			sc.read(bb);
			
			if(bb.hasRemaining() == false) {
				
				msgLen = bb.getInt(0);
				
				if(msgLen==0)
					return States.LENGTH; /*** KEEP-ALIVE ***/
				
				return States.MSG_ID;
			}
			
			return States.LENGTH;
			
		} catch(IOException ioe) {
			
			return States.SHUTDOWN;
		}
	}

}
